As a diver descends, substantial ambient pressure changes occur that can cause uncomfortable, sometimes painful, inward pressure on the eardrums. The simplest corrective procedure is to squeeze the nostrils while attempting to exhale through the nose which tends to force ambient pressure through the restriction of the eustachian tubes until inner ear pressure is equalized. With hands outside and nostrils inside the mask, some device is necessary to achieve clamping of the nostrils. Many masks have a lower wall sufficiently flexible as to allow it to be moved to close the nostrils sufficiently for the corrective procedure to take place. Other masks have pockets in the lower wall to allow the nostrils to be pinched between the diver's thumb and forefinger as the wall flexes. David L. Senne in his U.S. Pat. No. 3,027,561 points out that the pockets are not readily accessible because the usual breathing mouthpiece is in the way. Senne suggests the use of nose pincers with operating lever arms located in front of the face mask for ready access and for operation by one hand.
Senne's general approach is believed correct. However, Senne's solution leaves something yet to be desired for two reasons. First, Senne's pincers include two elements that pivot about spaced axes beneath the nostrils. The pincers angle inwardly and have a path of movement divergent from the natural path of nostril movement. Furthermore, the center of the pincers may miss the center of the nostrils so that a comfortable closing is not achieved. Finally, the lever ends are exposed and not neatly concealed.
In order to maximize underwater vision, the mask lens is desirably large. Yet the larger the mask, the more unstable it becomes on the wearer's head. A simple two point strap attachment may not be adequate to stabilize the mask. A four point strap attachment is therefore desirable for stability as well as for comfort.
The primary object of this invention is to provide an improved mask having novel means for proper nostril closure and having novel means for comfortable strap attachment.